A plain bearing or friction bearing generally comprises a metal shell having a lining of a bearing material which can also be a metal, lying in friction contact with a rotatable member such as a shaft.
The plain bearing or friction bearing (these terms being used interchangeably) thus is devoid of rolling elements of the type which constitutes roller bearings. For journaling a shaft, for example, they can be received in a bearing housing.
German Industrial Standard DIN 31 690 establishes a standard construction for such bearing housings which allows them to dissipate the thermal energy created by friction in the bearing in a highly effective way. The present invention, therefore, is principally directed to improving upon the type of plain-bearing housing within German Industrial Standard DIN 31 690.
As will be apparent from this industrial standard and as is generally the case in industry, to enable the bearing to be assembled onto the shaft, the bearing may be provided in two halves and/or the housing can be provided in two halves, a two-part housing being also useful when the bearing is a circumferentially continuous sleeve.
The two-part housing can comprise a lower housing part and an upper housing part which can be connected to the lower housing part along a junction which generally extends through the opening defined by the two housing parts and through which the shaft projects. Such housings may be upright stationary journals or plain-bearing housings or flange plain-bearing housings. In general the housings are provided with ribs to promote dissipation of heat, i.e. cooling.
The housing can also include means for closing the front side of the housing through which the bearing is accessible or which may be overhung by the plain bearing. When reference is made, therefore, to cooling ribs at least on one front side of the housing, it is intended to indicate that the cooling ribs can be provided on the front side of the housing which may carry the aforementioned closure although it should be noted that the cooling ribs will generally also be provided on the opposite side of the housing, i.e. both freely visible front sides of the housing can be provided with cooling ribs.
The above-mentioned German Industrial Standard describes a plain-bearing housing in which the upper part of the housing does not have such cooling ribs. In practice, however, it is common to provide the housing upper part with cooling ribs and the cooling ribs extend the full height of the lower part of the housing to the region of the junction or the shaft opening. Otherwise, apart from interruptions at which eyes for bolts or like structures are provided, a single rib lies in a single plane and extends the full height of the housing and remains in this plane even if interrupted by a bolt hole or the like.
The conventional plain-bearing housings have not proved to be altogether successful, especially for high-loading bearings, at least in part because the possibility of abstracting heating is limited. It is true that the dissipation of heat is a function of temperature and ambient conditions, but it has been frequently found that the life of the bearing shells has been limited because of insufficient heat dissipation.
Obviously one can use a force circulation in conjunction with such bearings to increase the heat dissipation therefrom, but this is generally uneconomical and involves significant complications because of the locations at which such bearings must be provided.
Furthermore, one cannot deviate materially from accepted industrial standards, namely the German Industrial Standard DIN 31 690 if the bearing housing is to have widespread acceptance.